Yes, I have the same experience too. I took the gmatprep, and got 2 incorrect answers in the first 15 questions, and got probably 80% incorrect on the last 20 questions, and still get a score of 48.
The case is slightly different for the verbal section. I got the first 15 questions correct (all of them), and answered 80% of the last 20 questions incorrectly, and only got a score of 34.
So that's why I'd like to know how the real test works?? (Especially those who have taken the test and scored in 90th+ percentile). Does Kaplan and PR strategies work (by concentrating on the first 15-20 questions), or should we really keep pace and try to answer each and every question correctly.
Thanks.